This invention relates to integrated circuits such as programmable logic device integrated circuits, and more particularly, to programmable logic device integrated circuits with dynamic phase alignment circuits.
Programmable logic devices are a type of integrated circuit that can be programmed by a user to implement a desired custom logic function. In a typical scenario, a logic designer uses computer-aided design tools to design a custom logic circuit. When the design process is complete, the tools generate configuration data. The configuration data is loaded into a programmable logic device to configure the device to perform the functions of the custom logic circuit.
In a typical system, a programmable logic device integrated circuit and other integrated circuits are mounted on a circuit board. The circuit board contains conductive paths that interconnect the integrated circuits. A system may also have paths that interconnect integrated circuits on different boards. Programmable logic devices contain transceiver circuitry for transmitting and receiving data over these communications paths.
Programmable logic device transceiver circuitry includes input and output drivers. The input and output drivers may use differential signaling schemes in which a pair of signals are referenced to each other or single-ended signaling schemes, in which signals are referenced to ground. In high-speed environments, the input and output drivers are generally differential drivers and handle differential signals.
In some programmable logic device architectures, complex transceiver circuitry is provided that supports many different operating modes. High-speed signals are handled by relying extensively on hardwired logic. While this type of arrangement may be satisfactory for some logic designs, the inclusion of complex transceiver circuitry is unnecessary for some designs and adds needless overhead. As a result, other programmable logic device architectures forgo complex transceiver circuitry and only support limited transceiver functionality such as source synchronous input-output signaling standards. Although these architectures dedicate less hardwired circuitry to processing incoming and outgoing data signals, they do not allow circuit designers to benefit from the different operating modes available with more complex transceiver architectures.
It would therefore be desirable to be able to provide integrated circuits such as programmable logic device integrated circuits with transceiver circuitry that supports a number of different operating modes without requiring the dedication of complex hardwired resources.